CVE-2026-1435 Overview
CVE-2026-1435 is a session management vulnerability in Graylog Web Interface version 2.2.3. The application issues a new sessionId on each successful authentication but fails to invalidate previously issued session identifiers. Older session tokens remain valid indefinitely across consecutive logins by the same user.
An attacker who obtains a leaked or stolen sessionId can reuse it to authenticate to the API or web interface on port 9000 or any HTTP/S endpoint. The flaw is tracked under CWE-613: Insufficient Session Expiration and was disclosed through an INCIBE Security Notice.
Critical Impact
An attacker with network access to the Graylog web service can reuse stolen session tokens to gain unauthorized access, interact with the API, and compromise affected account integrity.
Affected Products
- Graylog Web Interface 2.2.3
- Graylog deployments exposing port 9000
- Graylog HTTP/S API endpoints
Discovery Timeline
- 2026-02-18 - CVE-2026-1435 published to NVD
- 2026-02-18 - Last updated in NVD database
Technical Details for CVE-2026-1435
Vulnerability Analysis
The vulnerability resides in the session lifecycle logic of the Graylog Web Interface. When a user authenticates, the application generates a fresh sessionId and returns it to the client. The previous sessionId is not added to a revocation list, deleted from the session store, or otherwise marked invalid.
This behavior contradicts the secure session management principle that authentication events should invalidate prior sessions for the same identity. The result is an unbounded set of concurrently valid tokens per user account.
Root Cause
The root cause is improper session invalidation, classified as [CWE-613]. The authentication routine treats each login as an independent event rather than a state transition. No server-side cleanup runs against existing entries tied to the authenticating principal.
A leaked sessionId therefore retains its authorization grant until natural expiration, even after the legitimate user logs in again or rotates credentials.
Attack Vector
The attack requires network access to the Graylog web service on port 9000 or an equivalent HTTP/S endpoint. No privileges or user interaction are required to exploit a previously captured token.
Attackers obtain session identifiers through traffic interception, browser compromise, log file exposure, cross-site scripting, or shared workstation residue. With a valid sessionId, the attacker issues authenticated API requests, reads ingested log data, modifies pipelines, or alters user permissions depending on the original session's role.
The vulnerability mechanism is documented in the INCIBE Security Notice. No public proof-of-concept code is currently available.
Detection Methods for CVE-2026-1435
Indicators of Compromise
- Multiple active sessions for the same Graylog user account observed concurrently from different source IP addresses
- API requests bearing a sessionId issued before the user's most recent successful login
- Authenticated activity from geolocations inconsistent with the legitimate user's recent login origin
- Unexpected configuration changes, query patterns, or stream modifications under accounts with stale tokens
Detection Strategies
- Correlate Graylog access logs against authentication events to identify session IDs used after a subsequent login by the same user
- Monitor port 9000 and HTTPS endpoints for anomalous request rates or off-hours API activity
- Alert on session reuse from IP addresses or user-agent strings that differ from the originating login
Monitoring Recommendations
- Forward Graylog web interface and API logs to a centralized SIEM for cross-event correlation
- Track per-user session counts and flag accounts maintaining excessive concurrent sessions
- Audit privileged Graylog account activity, including role changes, stream deletions, and pipeline edits
How to Mitigate CVE-2026-1435
Immediate Actions Required
- Restrict network access to Graylog port 9000 and HTTP/S endpoints using firewall rules or VPN gating
- Force termination of all active sessions and require users to re-authenticate
- Rotate API tokens and service account credentials that may have transited the affected interface
- Review recent administrative actions in Graylog for unauthorized changes
Patch Information
No vendor patch is referenced in the available advisory data. Refer to the INCIBE Security Notice for vendor updates and upgrade guidance. Operators running Graylog 2.2.3 should plan migration to a supported release that implements proper session invalidation.
Workarounds
- Place Graylog behind a reverse proxy that enforces short session cookie lifetimes and re-authentication
- Terminate TLS at an upstream gateway and bind session cookies to client IP or device fingerprint where feasible
- Reduce server-side session timeout values to limit the validity window of leaked tokens
- Disable or tightly restrict accounts that no longer require access to the affected Graylog instance
# Example: restrict access to Graylog port 9000 to a management subnet
iptables -A INPUT -p tcp --dport 9000 -s 10.10.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 9000 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
